1 /* crypto/dh/dh_key.c */ 2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) 3 * All rights reserved. 4 * 5 * This package is an SSL implementation written 6 * by Eric Young (eay@cryptsoft.com). 7 * The implementation was written so as to conform with Netscapes SSL. 8 * 9 * This library is free for commercial and non-commercial use as long as 10 * the following conditions are aheared to. The following conditions 11 * apply to all code found in this distribution, be it the RC4, RSA, 12 * lhash, DES, etc., code; not just the SSL code. The SSL documentation 13 * included with this distribution is covered by the same copyright terms 14 * except that the holder is Tim Hudson (tjh@cryptsoft.com). 15 * 16 * Copyright remains Eric Young's, and as such any Copyright notices in 17 * the code are not to be removed. 18 * If this package is used in a product, Eric Young should be given attribution 19 * as the author of the parts of the library used. 20 * This can be in the form of a textual message at program startup or 21 * in documentation (online or textual) provided with the package. 22 * 23 * Redistribution and use in source and binary forms, with or without 24 * modification, are permitted provided that the following conditions 25 * are met: 26 * 1. Redistributions of source code must retain the copyright 27 * notice, this list of conditions and the following disclaimer. 28 * 2. Redistributions in binary form must reproduce the above copyright 29 * notice, this list of conditions and the following disclaimer in the 30 * documentation and/or other materials provided with the distribution. 31 * 3. All advertising materials mentioning features or use of this software 32 * must display the following acknowledgement: 33 * "This product includes cryptographic software written by 34 * Eric Young (eay@cryptsoft.com)" 35 * The word 'cryptographic' can be left out if the rouines from the library 36 * being used are not cryptographic related :-). 37 * 4. If you include any Windows specific code (or a derivative thereof) from 38 * the apps directory (application code) you must include an acknowledgement: 39 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" 40 * 41 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND 42 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 43 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 44 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 45 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 46 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 47 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 48 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 49 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 50 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 51 * SUCH DAMAGE. 52 * 53 * The licence and distribution terms for any publically available version or 54 * derivative of this code cannot be changed. i.e. this code cannot simply be 55 * copied and put under another distribution licence 56 * [including the GNU Public Licence.] 57 */ 58 59 #include <stdio.h> 60 #include "cryptlib.h" 61 #include <openssl/bn.h> 62 #include <openssl/rand.h> 63 #include <openssl/dh.h> 64 65 #ifndef OPENSSL_FIPS 66 67 static int generate_key(DH *dh); 68 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh); 69 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 70 const BIGNUM *a, const BIGNUM *p, 71 const BIGNUM *m, BN_CTX *ctx, 72 BN_MONT_CTX *m_ctx); 73 static int dh_init(DH *dh); 74 static int dh_finish(DH *dh); 75 76 int DH_generate_key(DH *dh) 77 { 78 return dh->meth->generate_key(dh); 79 } 80 81 int DH_compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 82 { 83 return dh->meth->compute_key(key, pub_key, dh); 84 } 85 86 static DH_METHOD dh_ossl = { 87 "OpenSSL DH Method", 88 generate_key, 89 compute_key, 90 dh_bn_mod_exp, 91 dh_init, 92 dh_finish, 93 0, 94 NULL, 95 NULL 96 }; 97 98 const DH_METHOD *DH_OpenSSL(void) 99 { 100 return &dh_ossl; 101 } 102 103 static int generate_key(DH *dh) 104 { 105 int ok=0; 106 int generate_new_key=0; 107 unsigned l; 108 BN_CTX *ctx; 109 BN_MONT_CTX *mont=NULL; 110 BIGNUM *pub_key=NULL,*priv_key=NULL; 111 112 ctx = BN_CTX_new(); 113 if (ctx == NULL) goto err; 114 115 if (dh->priv_key == NULL) 116 { 117 priv_key=BN_new(); 118 if (priv_key == NULL) goto err; 119 generate_new_key=1; 120 } 121 else 122 priv_key=dh->priv_key; 123 124 if (dh->pub_key == NULL) 125 { 126 pub_key=BN_new(); 127 if (pub_key == NULL) goto err; 128 } 129 else 130 pub_key=dh->pub_key; 131 132 133 if (dh->flags & DH_FLAG_CACHE_MONT_P) 134 { 135 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, 136 CRYPTO_LOCK_DH, dh->p, ctx); 137 if (!mont) 138 goto err; 139 } 140 141 if (generate_new_key) 142 { 143 l = dh->length ? dh->length : BN_num_bits(dh->p)-1; /* secret exponent length */ 144 if (!BN_rand(priv_key, l, 0, 0)) goto err; 145 } 146 147 { 148 BIGNUM local_prk; 149 BIGNUM *prk; 150 151 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) 152 { 153 BN_init(&local_prk); 154 prk = &local_prk; 155 BN_with_flags(prk, priv_key, BN_FLG_CONSTTIME); 156 } 157 else 158 prk = priv_key; 159 160 if (!dh->meth->bn_mod_exp(dh, pub_key, dh->g, prk, dh->p, ctx, mont)) goto err; 161 } 162 163 dh->pub_key=pub_key; 164 dh->priv_key=priv_key; 165 ok=1; 166 err: 167 if (ok != 1) 168 DHerr(DH_F_GENERATE_KEY,ERR_R_BN_LIB); 169 170 if ((pub_key != NULL) && (dh->pub_key == NULL)) BN_free(pub_key); 171 if ((priv_key != NULL) && (dh->priv_key == NULL)) BN_free(priv_key); 172 BN_CTX_free(ctx); 173 return(ok); 174 } 175 176 static int compute_key(unsigned char *key, const BIGNUM *pub_key, DH *dh) 177 { 178 BN_CTX *ctx=NULL; 179 BN_MONT_CTX *mont=NULL; 180 BIGNUM *tmp; 181 int ret= -1; 182 int check_result; 183 184 if (BN_num_bits(dh->p) > OPENSSL_DH_MAX_MODULUS_BITS) 185 { 186 DHerr(DH_F_COMPUTE_KEY,DH_R_MODULUS_TOO_LARGE); 187 goto err; 188 } 189 190 ctx = BN_CTX_new(); 191 if (ctx == NULL) goto err; 192 BN_CTX_start(ctx); 193 tmp = BN_CTX_get(ctx); 194 195 if (dh->priv_key == NULL) 196 { 197 DHerr(DH_F_COMPUTE_KEY,DH_R_NO_PRIVATE_VALUE); 198 goto err; 199 } 200 201 if (dh->flags & DH_FLAG_CACHE_MONT_P) 202 { 203 mont = BN_MONT_CTX_set_locked(&dh->method_mont_p, 204 CRYPTO_LOCK_DH, dh->p, ctx); 205 if ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) == 0) 206 { 207 /* XXX */ 208 BN_set_flags(dh->priv_key, BN_FLG_CONSTTIME); 209 } 210 if (!mont) 211 goto err; 212 } 213 214 if (!DH_check_pub_key(dh, pub_key, &check_result) || check_result) 215 { 216 DHerr(DH_F_COMPUTE_KEY,DH_R_INVALID_PUBKEY); 217 goto err; 218 } 219 220 if (!dh->meth->bn_mod_exp(dh, tmp, pub_key, dh->priv_key,dh->p,ctx,mont)) 221 { 222 DHerr(DH_F_COMPUTE_KEY,ERR_R_BN_LIB); 223 goto err; 224 } 225 226 ret=BN_bn2bin(tmp,key); 227 err: 228 if (ctx != NULL) 229 { 230 BN_CTX_end(ctx); 231 BN_CTX_free(ctx); 232 } 233 return(ret); 234 } 235 236 static int dh_bn_mod_exp(const DH *dh, BIGNUM *r, 237 const BIGNUM *a, const BIGNUM *p, 238 const BIGNUM *m, BN_CTX *ctx, 239 BN_MONT_CTX *m_ctx) 240 { 241 /* If a is only one word long and constant time is false, use the faster 242 * exponenentiation function. 243 */ 244 if (a->top == 1 && ((dh->flags & DH_FLAG_NO_EXP_CONSTTIME) != 0)) 245 { 246 BN_ULONG A = a->d[0]; 247 return BN_mod_exp_mont_word(r,A,p,m,ctx,m_ctx); 248 } 249 else 250 return BN_mod_exp_mont(r,a,p,m,ctx,m_ctx); 251 } 252 253 254 static int dh_init(DH *dh) 255 { 256 dh->flags |= DH_FLAG_CACHE_MONT_P; 257 return(1); 258 } 259 260 static int dh_finish(DH *dh) 261 { 262 if(dh->method_mont_p) 263 BN_MONT_CTX_free(dh->method_mont_p); 264 return(1); 265 } 266 267 #endif 268